There is much interest in layered clay based polymer nanocomposites because of the improved properties exhibited by the nanocomposites when compared to the pure polymer. It is widely known, however, that some mechanical properties, such as elongation-at-break, are often reduced considerably upon the addition of the clay. It is desirable to maximize delamination of the platelet particles into individual platelets in order to maximize sorte property improvements, including barrier improvements, and to minimize deleterious effects on some properties including elongation-at-break.
This invention relates to processes to prepare polyester composite compositions and to polyester composite materials which comprise a polyester polymer and a swellable layered clay mineral that has been intercalated with polyalkoxylated ammonium salts.
The polyester composite materials of this invention are useful for forming packages that have improved gas barrier properties. Containers made from these polyester composite materials are ideally suited for protecting consumable products, such as foodstuffs, soft drinks, and medicines.
U.S. Pat. No. 4,739,007 discloses polyamide composite materials containing layered clay mineral intercalated with organic onium salis. Polyalkoxylated ammonium salts as disclosed in this invention report were not described.
U.S. Pat. No. 5,164,460 discloses polyimide composite materials containing ayered clay mineral intercalated with organic onium salts. Polyalkoxylated ammonium salts as disclosed in this invention report were not described.
WO 93/04118 relates to an extrusion compounding process for forming polymeric composites which are comprised of platelet particles containing organic onium salts and dispersed in a polymeric matrix. Polyalkoxylated ammonium salts as disclosed in this invention were not described. Further, as shown in the present Examples, extrusion compounding processes alone do not provide polyester composites containing mostly individual platelet particles.
U.S. Pat. No. 4,889,885 describes the polymerization of various vinyl monomers such as methyl methacrylate and isoprene in the presence of sodium montmorillonite. In Example 11, it describes the polycondensation of dimethyl terephthalate and ethylene glycol in the presence of 33 weight percent of a montmorillonite clay in water to provide 6.2 wt % clay in the final composite. Water or alcohol is needed in this process as a medium for predispersion of the clay to allow intercalation by monomer. It is known that the addition of water to dimethyl terephthalate and ethylene glycol preparations of PET reduces the rate of reaction, reduces the I.V. that can be attained, and often produces haze.
U.S. Pat. No. 5,336,647 and 5,429,999 describe the preparation of layered clays containing polyalkoxylated ammonium salts. Use of these clays in polyesters was not recognized.
Among the numerous patents that describe the preparation of layered clays containing ammonium salts are U.S. Pat. Nos. 2,531,427; 2,966,506; 4,081,496; 4,105,578; 4,116,866; 4,208,218; 4,391,637; 4,410,364; 4,412,018; 4,434,075; 4,434,076; 4,450,095; 4,517,112; 4,677,158; 4,769,078; 5,110,501; and 5,334,241.
JP Kokai patent no. 9-176461 discloses polyester bottles wherein the polyester contains swellable laminar silicate. WO 97/31057 discloses polymer composites having dispersed therein inorganic material such as clay which is separated with an inorganic intercalant. WO 97/31973 discloses producing a composite material by mixing a potassium ionomer in which ethylene methacrylate copolymer is either partially or completely neutralized with an organic polymer. Polyalkoxylated ammonium salts as disclosed in this invention were not described Moreover, the foregoing references produce materials comprising very large tactoids and little if any dispersion of individual platelet particles.